Solution containing a nitroxide radical for magnetometry by nuclear magnetic resonance

Abstract

The invention relates to a solution containing a nitroxide radical for magnetometry by nuclear magnetic resonance. This solution is constituted by a nitroxide radical of formula: ##STR1## in which R 1 , R 2 , R 3 and R 4 , which can be the same or different, represent an alkyl group or an alkoxy group which may be deuterated, or in which the pairs R 1 -R 2 and/or R 3 -R 4 together form an optionally deuterated cycloalkyl or polycycloalkyl group, and N represent 14 N or 15 N, dissolved in a solvent having an oxidizing power and an appropriate viscosity. The solvent can be constituted by a mixture of water and two compounds respectively playing the part of the oxidizing agent and viscosity modifying agent, e.g. water, ethylene glycol and NalO 4 , or can be solely constituted by a mixture of water and an oxidizing agent able to modify the viscosity, such as acetic acid.

We claim: 
     
       1. Solution containing a nitroxide radical for magnetometry by nuclear magnetic resonance, said solution comprising a nitroxide radical of formula: ##STR9## in which R 1 , R 2 , R 3  and R 4 , which can be the same or different, represent an optionally deuterated alkyl or alkoxy group, or in which the pairs R 1  -R 2  and/or R 3  -R 4  together form an optionally deuterated cycloalkyl or poly-cycloalkyl group, and N represents  14  N or  15  N; a solvent comprising water and from 20 to 30 volume percent ethylene glycol; and an oxidizing agent of the reduced form of the nitroxide radical. 
     
     
       2. Solution according to claim 1, characterized in that R 1 , R 2 , R 3  and R 4  represent the optionally deuterated methyl group. 
     
     
       3. Solution according to claim 1, characterized in that N represents  15  N. 
     
     
       4. Solution according to claim 1, characterized in that the oxidizing agent is chosen from among metaperiodates of alkali metals and lead dioxide. 
     
     
       5. Solution according to claim 1, characterized in that the oxidizing agent is sodium metaperiodate. 
     
     
       6. Solution according to claim 1, characterized in that it contains 10 -2  to 5.10 -2  mole/l of oxidizing agent. 
     
     
       7. Solution according to claim 1, characterized in that it contains 10 -3  to 10 -2  mole/l of nitroxide radical. 
     
     
       8. Nuclear magnetic resonance magnetometer probe without forbidden axis having two assemblies, each constituted by a coil surrounding a container filled with a sample constituted by a solution containing a nitroxide radical, and two resonant cavities for exciting the two samples to two different frequencies, characterized in that the two samples are a solution of a nitroxide radical according to claim 1. 
     
     
       9. Solution containing a nitroxide radical for magnetometry by nuclear magnetic resonance, said solution comprising a nitroxide radical of formula: ##STR10## in which R 1 , R 2 , R 3  and R 4 , which can be the same or different, represent an optionally deuterated alkyl or alkoxy group, or in which the pairs R 1  -R 2  and/or R 3  -R 4  together form an optionally deuterated cycloalkyl or poly-cycloalkyl group, and N represents  14  N or  15  N; and a solvent comprising water and from 20 to 50 volume percent acetic acid. 
     
     
       10. Solution according to claim 9, characterized in that it is constituted by 1,1,3,3-tetramethylisoindolin-2-yloxyl dissolved at a concentration of 10 -3  mole/l in a mixture of water and acetic acid containing 50 vol. % acetic acid. 
     
     
       11. Solution according to claim 9, characterized in that it contains 10 -3  to 10 -2  mole/l of nitroxide radical.